/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineIdentityInterface.h
Account credentials needed to sign in to an online service
class FOnlineAccountCredentials
FString
Id
Id of the user logging in (email, display name, facebook id, etc)
FString
Token
Credentials of the user logging in (password or auth token)
FString
Type
Type of account. Needed to identity the auth method to use (epic, internal, facebook, etc)